JP2012189245A - Heat storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat storage device that can increase the heat storage density of an entire device without getting larger in size while still maintaining a large heat transfer area density.SOLUTION: The heat storage device 1 in which filling spaces for a latent heat storage material 9 and liquid flow paths for a heat medium 10 are alternately provided by stacking plates 3 for a heat storage material and plates 4 for a heat storage medium, includes: a porous metal 8 provided in the filling spaces for the latent heat storage material 9. The latent heat storage material 9 is filled in pores of the porous metal 8.

Description

  The present invention relates to a heat storage device using latent heat storage, and particularly to a heat storage device using a plurality of heat exchange plates.

  Generally, as a heat storage material used in a heat storage device, a sensible heat storage material that uses only a temperature change of a substance and a latent heat storage material that uses heat absorption and release accompanying phase changes such as melting and solidification of the substance are known. . It is also known that latent heat has a higher heat storage density than sensible heat, and a large heat storage can be expected with a latent heat storage material.

However, since the latent heat storage material is accompanied by a phase change, a solid layer is deposited on the heat transfer surface and the deposited layer becomes thicker with time, so the thermal resistance increases and the heat output decreases. There is.
In order to solve the above problems and increase the heat output, it is effective to increase the heat transfer area density. As a representative example of this, a plate-type stacked heat storage device has been proposed (for example, see Patent Document 1). .

  The heat storage device described in Patent Document 1 has a plate heat exchanger structure in which a plurality of heat exchange plates are stacked, and allows a gap filled with a latent heat storage material and a heat medium (such as water or air) to pass therethrough. The gaps are alternately formed. Thus, by forming a narrow gap between the plates, the heat transfer area per volume is increased, and a decrease in heat transfer rate due to precipitation of a solid layer is prevented.

JP-A-60-162187

  As in Patent Document 1, the conventional heat storage device has a heat storage material filling space (a space for filling the latent heat storage material) and a heat medium passage space in order to prevent an increase in thermal resistance due to solid layer deposition of the latent heat storage material. (The gap through which the heat medium passes) are alternately arranged, the filling rate of the latent heat storage material is reduced to about half, and the heat storage density of the heat storage device is also half of the heat storage density as a physical property of the heat storage material Since it fell to the extent, there existed a subject that the whole apparatus enlarged.

  The present invention has been made to solve the above-described problems, and can increase the heat storage density of the entire apparatus while avoiding an increase in the size of the entire apparatus while maintaining a large heat transfer area density. The purpose is to obtain a heat storage device.

  A heat storage device according to the present invention is a heat storage device in which a plurality of plates are stacked and a latent heat storage material filling space and a heat medium passage space are alternately installed, and provided in the latent heat storage material filling space. The latent heat storage material is provided with the porous metal filled in the pores of the porous metal.

  According to the present invention, while maintaining a large heat transfer area density, it is possible to increase the filling density of the latent heat storage material while preventing a decrease in the heat transfer speed of the latent heat storage material, thereby realizing a compact heat storage device. be able to.

It is a perspective view which shows the external appearance of the thermal storage apparatus which concerns on Embodiment 1 of this invention. It is a sectional side view which expands and shows a part of center part of the thermal storage apparatus of FIG. It is a front view which expand | deploys and shows the planar shape part of each plate of the thermal storage apparatus of FIG. It is explanatory drawing which shows the fall characteristic of the heat transfer rate in case the layer of the latent heat storage material used in Embodiment 1 of this invention is thick. It is explanatory drawing which shows the average cell size and porosity of the metal foam in Embodiment 1 of this invention. It is explanatory drawing which shows the heat conductivity in the plate for thermal storage materials in Embodiment 1 of this invention. It is explanatory drawing which shows the amount of latent heat storage per volume in Embodiment 1 of this invention.

Embodiment 1 FIG.
1 is a perspective view showing an appearance of a heat storage device 1 according to Embodiment 1 of the present invention.
2 is an enlarged side sectional view showing a part of the central portion of the heat storage device 1, and FIG. 3 is a front view showing the flat shape portion of each laminated plate constituting the heat storage device 1 in an expanded manner. .

  1 to 3, the heat storage device 1 generally includes an end plate 2, a heat storage material plate 3 filled with a latent heat storage material 9, and a heat medium plate 4 serving as a flow path of the heat medium 10. It has a laminated structure.

  In FIG. 1, the end plate 2 includes a heat storage section manifold inlet section 5 that also serves as an introduction section of the latent heat storage material 9, a heat medium inlet 6 through which the heat medium 10 is introduced, and a heat medium through which the heat medium 10 is led out. An outlet 7 projects outwardly.

1 and 2, the heat storage material plate 3 and the heat medium plate 4 have a casing shape without a lid, and the end plate 2 made of a flat plate is a laminated structure (the heat storage material plate 3 at the end). Functions as a lid.
1 and 2 show an example in which four heat storage material plates 3 and three heat medium plates 4 are stacked as an example, but an arbitrary number of stacked structures are used. Is possible.

The plate for heat storage material 3 and the plate for heat medium 4 can arbitrarily set the drawing depth by pressing a thin plate such as stainless steel.
An uneven portion (not shown) is formed on each surface of the heat storage material plate 3 and the heat medium plate 4 in order to enlarge the heat transfer area.

A temperature sensor (not shown) is installed inside the heat storage material plate 3 and the heat medium plate 4.
Further, the outer periphery of the heat storage device 1 is covered with a heat insulating material (not shown) in order to reduce heat loss to the outside.

Both the heat storage material plate 3 and the heat medium plate 4 have a U-shaped storage shape, but in FIG. 2, the planar shape of the central portion of the heat storage material plate 3 and the heat medium plate 4. Only the part is shown.
In FIG. 2, the depth a of the heat storage material plate 3 (thickness of the layer of the latent heat storage material 9) is larger than the depth b of the heat medium plate 4 (thickness of the flow path space of the heat medium 10). Is set to a value.

  In the heat storage material plate 3 sealed on the back surface of the end plate 2 and in the heat storage material plate 3 sealed on the back surface of the heat medium plate 4, porous metal 8 such as foam metal, respectively. The latent heat storage material 9 is introduced into the pores of the porous metal 8 from the heat storage section manifold inlet 5 in advance.

  On the other hand, when the heat storage device 1 is used (described later), in the heat medium plate 4 sealed on the back surface of the heat storage material plate 3, a heat medium 10 made of a fluid (for example, high-temperature water), It passes in the direction of the broken line arrow in FIG. 2 from the heat medium inlet 6 toward the heat medium outlet 7.

  As the porous metal 8, foam metal, metal wool, sintered metal, metal honeycomb, laminated metal mesh, and the like are used in order to satisfy the required function of transferring heat with high efficiency in the thickness direction.

  In FIG. 3, on the end face of the end plate 2, a heat storage material introduction hole 11A to which the heat storage unit manifold inlet 5 (see FIG. 1) is connected, a heat medium inlet hole 12A to which the heat medium inlet 6 is connected, and heat A heat medium outlet hole 13A to which the medium outlet 7 is connected is provided.

Further, at the positions corresponding to the heat storage material introduction hole 11A, the heat medium inlet hole 12A, and the heat medium outlet hole 13A of the end plate 2, the heat storage material plate 3 includes the heat storage material introduction hole 11B, the heat medium inlet hole 12B, and the heat. A medium outlet hole 13B is provided.
Similarly, the heat medium plate 4 is provided with a heat storage material introduction hole 11C, a heat medium inlet hole 12C, and a heat medium outlet hole 13C.

  However, in the heat storage material plate 3 arranged on the outermost side (the side opposite to the end plate 2), in order to prevent the latent heat storage material 9 and the heat medium 10 from flowing out to the outside, the heat storage material introduction hole 11B shown in FIG. The heat medium inlet hole 12B and the heat medium outlet hole 13B are not provided.

The heat storage material introduction holes 11A, 11B, and 11C are communicated by a laminated structure of the end plate 2, the heat storage material plate 3, and the heat medium plate 4 to form a part of the heat storage unit manifold and the heat storage unit manifold inlet 5 The heat storage section manifold is formed as a whole.
Similarly, the heat medium inlet holes 12A, 12B, and 12C communicate with the heat medium inlet 6, and the heat medium outlet holes 13A, 13B, and 13C communicate with the heat medium outlet 7 to form a flow path of the heat medium 10.

The heat storage material plate 3 is provided with a packing 14 </ b> B for dividing the space of the latent heat storage material 9 and a packing 15 </ b> B for dividing the space of the heat medium 10.
Further, the heat medium plate 4 is provided with a packing 14 </ b> C for dividing the section of the heat medium 10 and a packing 15 </ b> C for dividing the space of the latent heat storage material 9.

As shown in FIG. 3, each packing 14B, 14C, 15B, 15C is a symmetrical system and has substantially the same shape.
As a material for the packings 14B, 14C, 15B, and 15C, a material that is highly corrosive with respect to the latent heat storage material 9, such as a synthetic rubber or a hollow metal, is selected.

In the case of configuring the heat storage device 1 of FIG. 1, first, the molten latent heat storage material 9 is introduced from the heat storage section manifold inlet section 5 that also serves as the heat storage material introduction section.
The latent heat storage material 9 passes through the heat storage section manifold formed by the heat storage material introduction holes 11A, 11B, and 11C, flows into the space divided by the packing 14B of the four heat storage material plates 3, and the heat storage material plate 3 Are filled in the pores of the porous metal 8 provided in the inside.

When the latent heat storage material 9 is filled into the porous metal 8 in the space divided by the packing 14B of the heat storage material plate 3, the heat storage material introduction holes 11A, 11B, 11C and the heat storage unit manifold inlet 5 The latent heat storage material 9 is also filled in the interior of the heat storage section manifold formed by.
At this time, the latent heat storage material 9 is not filled in the whole of the heat storage section manifold, but is filled slightly in a small amount so that a buffer space (air layer) is formed in a part of the upper part of the heat storage layer. .

Here, the effect when the buffer space is provided in the heat storage layer of the latent heat storage material 9 will be described.
The density per volume of the latent heat storage material 9 is about 1.3 [kg / L] at the time of melting (when liquid), and about 1.5 [kg / L] at the time of solidification (when solid). About 15% volume change occurs during solidification.

In order to absorb the volume change (15%), an air layer buffer space is provided in the heat storage unit manifold.
Thereby, even when the volume is increased by the phase change of the latent heat storage material 9, the volume change is absorbed by the buffer space, so that the thermal stress applied to the heat storage material plate 3 and the heat medium plate 4 is reduced. And deformation and breakage of the apparatus can be prevented.

On the other hand, the heat medium 10 is introduced from the heat medium inlet 6, passes through the heat medium inlet hole 12 </ b> B of the heat storage material plate 3, flows into the space divided by the packing 14 </ b> C of the heat medium plate 4, and heat It passes through the medium inlet hole 12 </ b> C and flows into the next heat medium plate 4.
The heat medium 10 that has flowed through the space divided by the packing 14 </ b> C flows out of the heat medium outlet 7 through the heat medium outlet hole 13 </ b> C.

Next, operation | movement at the time of use of the thermal storage apparatus 1 which concerns on Embodiment 1 of this invention shown in FIGS. 1-3 is demonstrated more concretely.
First, high-temperature water having a melting point or higher of the latent heat storage material 9 is introduced from the heat medium inlet 6 as the heat medium 10. For example, when sodium acetate trihydrate is used as the latent heat storage material 9, since the melting point of the latent heat storage material 9 is 58 ° C., hot water of about 70 ° C. is introduced as the heat medium 10.

As shown in FIG. 2, the heat medium 10 (high temperature water) flows through the heat medium plate 4 and melts the latent heat storage material 9 inside the adjacent heat storage material plate 3.
Next, when the detected value of each temperature sensor provided inside the heat storage material plate 3 and the heat medium plate 4 indicates a temperature that is approximately approximate, it is determined that the latent heat storage material 9 has melted, The introduction of the heat medium 10 (hot water) is stopped.

  Even after the introduction of the heat medium 10 (high temperature water) is stopped, the temperature of the molten latent heat storage material 9 is unlikely to decrease due to the effect of the heat insulating material covering the heat storage device 1, and it takes a long time for the latent heat storage material 9 to solidify. Cost.

  When the latent heat storage material 9 is solidified after a long time until the heat is extracted from the heat storage device 1, the solidified state can be detected by the temperature sensor inside the plate 3 for the heat storage material. Hot water) may be introduced again to melt the latent heat storage material 9.

On the other hand, when the heat medium 10 needs heat, cold water having a melting point or less (for example, about 20 ° C.) of the latent heat storage material 9 is introduced from the heat medium inlet 6 to exchange heat with the latent heat of the latent heat storage material 9. Then, it is taken out from the heat medium outlet 7 as high-temperature water close to the melting point (58 ° C.) of the latent heat storage material 9.
In the case of taking out heat, the flow path of the heat medium 10 may be set in reverse, and a flow path for introducing cold water from the heat medium outlet 7 and taking it out from the heat medium inlet 6 may be used.

Next, the effect of the porous metal 8 inside the heat storage material plate 3 will be described with reference to FIGS. 4 to 6, taking as an example the case where a foam metal is used as the porous metal 8.
As the foam metal material, aluminum, copper, nickel, and the like are commercially available, and an appropriate material can be selected in consideration of good thermal conductivity and corrosivity due to the latent heat storage material 9. The case where a foam metal is used will be described.

Here, sodium acetate trihydrate is used as the latent heat storage material 9.
In this case, the thermal conductivity of the latent heat storage material 9 made of sodium acetate trihydrate is 0.41 [W / (m · K)] in the molten state and 0.65 [W / (m · K) in the solidified state. )], Both of which are small values.

Further, when the latent heat storage material 9 starts to solidify in the vicinity of the heat storage material plate 3, the fluidity decreases and the thermal resistance increases, and the heat transfer rate representing the heat transfer rate gradually decreases.
FIG. 4 is an explanatory diagram showing a decrease characteristic of the heat transfer coefficient when the layer of the latent heat storage material 9 is thick, the horizontal axis is the elapsed time [min], and the vertical axis is the heat transfer coefficient [W / m2 ° C.].

  In FIG. 4, as a representative example of the latent heat storage material 9, a measurement result is shown in the case where cold water is flown inside a copper pipe having an inner diameter of 3 mm and an outer diameter of 4 mm and the outer periphery of the copper pipe is filled with sodium acetate trihydrate. It can be seen that the heat transfer coefficient gradually decreases with time.

On the other hand, when sodium acetate trihydrate is filled with an aluminum foam metal, the thermal conductivity is improved.
FIG. 5 is an explanatory view showing the specifications (average cell size and porosity) of the foam metal, and FIG. 6 is an explanatory view showing the thermal conductivity in the heat storage material plate 3.

The thermal conductivity when sodium acetate trihydrate is filled with the foam metal of aluminum with the specifications (average cell size, porosity) of the foam metal shown in FIG. 5 is expressed as shown in FIG.
Note that the thermal conductivity of pure aluminum is 237 [W / (m · K)]. However, assuming that impurities are mixed, the thermal conductivity of aluminum is 190 [W / ( m · K)].

As shown in FIG. 5, when the four types of foam metals A to D are filled with sodium acetate trihydrate, the heat conductivity inside the heat storage material plate 3 is as shown in FIG. 6. .
As shown in FIG. 6, the thermal conductivity inside the heat storage material plate 3 is increased to 2.39 to 3.61 [W / (m · K)] by using aluminum foam metal.
Therefore, compared to the thermal conductivity (0.41 to 0.65 [W / (m · K)]) when sodium acetate trihydrate is used alone, the thermal conductivity is very large. I understand.

  Thus, by using the porous metal 8 such as a foam metal made of a metal having a large thermal conductivity together with the latent heat storage material 9, the thermal conductivity inside the plate 3 for the thermal storage material can be improved. Even if the depth a of the heat storage material plate 3 (thickness of the layer of the latent heat storage material 9) is set large, the heat transfer speed does not decrease (see FIG. 4).

Next, the relationship between the depth a of the heat storage material plate 3 and the depth b of the heat medium plate 4 (see FIG. 2) will be described with reference to FIG.
FIG. 7 is an explanatory diagram showing the relationship between the depths a and b and the latent heat storage amount per volume (latent heat storage density) [kJ / L].

FIG. 7 shows the latent heat storage amount when the depth a of the heat storage material plate 3 is changed based on the depth b of the heat medium plate 4.
Further, when the depths a and b are set to the ratios as shown in FIG. 7, the filling rate value a / (a + b) of the latent heat storage material 9 in the heat storage device 1 is also shown.

The latent heat storage amount per volume of sodium acetate trihydrate is about 335 [kJ / L].
In FIG. 7, in a general plate-type stacked heat storage device having a filling rate value of “a / (a + b) = 0.50 (a = 1, b = 1)”, the heat storage device 1 per volume The latent heat storage amount is reduced to 160 [kJ / L].

Here, the case where the foam metal B (refer FIG. 5) whose porosity of the porous metal 8 is 0.954 is used together with sodium acetate trihydrate is shown.
On the other hand, when the value of the filling rate is set large up to “a / (a + b) = 0.80 (a = 4, b = 1)”, the latent heat storage amount per volume of the heat storage device 1 is 256 [kJ / L].

When metal wool is used as the porous metal 8, it has some elasticity, so the thickness of the metal wool is set slightly larger than the depth a of the heat storage material plate 3, and the heat storage material plate 3. And by compressing and installing with the heat medium plate 4, the contact property with each plate can be improved.
Steel wool is a typical example of metal wool, but copper wool, brass wool, aluminum wool, and the like are also applicable.

Further, when a sintered metal is used as the porous metal 8, it is handled in the same manner as the foam metal.
Since the metal wool and sintered metal have continuous pores in the flow direction (lateral direction) like the foam metal, the heat storage material introduction hole can be obtained by pouring the molten latent heat storage material 9 from the heat storage section manifold inlet 5. The latent heat storage material 9 can be filled in the entire porous metal 8 inside the packing 14B through 11A, 11B, and 11C.

Further, when a metal honeycomb is used as the porous metal 8, a metal skeleton is required for the honeycomb wall to transmit heat in the thickness direction. In the honeycomb structure, since there are no pores in the flow direction (lateral direction), the method of pouring the molten latent heat storage material 9 from the heat storage unit manifold inlet 5 fills the entire interior of the metal honeycomb with the latent heat storage material 9. I can't.
Therefore, in this case, the latent heat storage material 9 previously melted in the state of the metal honeycomb alone is filled in all the cells of the honeycomb, and the latent heat storage material 9 is solidified and integrated with the metal honeycomb, and then the plate 3 for the heat storage material. The installation method is applied.

Further, when a metal mesh laminated as the porous metal 8 is used, a structure in which a large number of irregularities are randomly provided on the metal mesh to form a metal skeleton that transmits heat in the thickness direction is used. Applied.
Thereby, the metal mesh part which the uneven | corrugated | grooved part contacted becomes a metal skeleton which conveys heat, and can fill the inside of the uneven | corrugated | grooved part with the latent heat storage material 9. FIG.

As described above, in the heat storage device 1 according to Embodiment 1 (FIGS. 1 to 3) of the present invention, a plurality of plates (the plate for heat storage material 3 and the plate for heat medium 4) are laminated to form a latent heat storage material. Nine filling spaces and flow space of the heat medium 10 are alternately arranged.
The porous metal 8 is provided in the space filled with the latent heat storage material 9, and the latent heat storage material 9 is filled in the pores of the porous metal 8.

Thus, in the inside of the heat storage material plate 3 (the space filled with the latent heat storage material 9), the porous metal 8 for improving the heat transfer rate of the latent heat storage material 9 is installed. By using a combination of the sintered metal or the like and the latent heat storage material 9, it becomes possible to increase the thermal conductivity inside the latent heat storage material 9 and improve the heat storage effect.
Further, the depth a of the heat storage material plate 3 (the thickness of the layer of the latent heat storage material 9) can be set sufficiently large, and the heat storage density of the heat storage device 1 can be increased.

  Further, the heat storage device 1 according to Embodiment 1 of the present invention has a plate-type laminated structure, and the depth a of the heat storage material plate 3 (the thickness of the layer in the filling space of the latent heat storage material 9) is The porosity is set to a value larger than the thickness b of the heat medium plate 4 (thickness of the layer of the flow path space of the heat medium 10) and improves the heat transfer rate of the thick latent heat storage material 9. Metal 8 is installed.

  As a result, the thermal conductivity of the latent heat storage material 9 can be increased, and the filling space of the latent heat storage material 9 can be set thick. Therefore, the ratio of the latent heat storage material 9 to the entire heat storage device 1 The heat storage density of the heat storage device 1 can be increased.

  In Embodiment 1 of the present invention, the filling space of the latent heat storage material 9 is composed of a plurality of stacked spaces, and the heat storage device 1 has a manifold space that communicates all of the filling spaces of the latent heat storage material 9. The manifold space has a buffer space that is not filled with the latent heat storage material 9.

  Thus, by providing the buffer space that is not filled with the latent heat storage material 9, even if the volume is increased by the phase change of the latent heat storage material 9, the volume change is absorbed in the buffer space. The thermal stress applied to the heat medium plate 4 can be reduced, and deformation and breakage of the heat storage device 1 can be prevented.

Further, the porous metal 8 is formed of foam metal, metal wool, sintered metal, metal honeycomb, or laminated metal mesh.
Thus, the thermal conductivity of the heat storage layer can be increased by using the porous metal 8 having a larger thermal conductivity than the latent heat storage material 9 in combination.

  DESCRIPTION OF SYMBOLS 1 Thermal storage apparatus, 2 End plate, 3 Thermal storage material plate, 4 Thermal medium plate, 5 Thermal storage part manifold inlet part, 6 Thermal medium inlet, 7 Thermal medium outlet, 8 Porous metal, 9 Latent heat storage material, 10 Thermal medium , 11A, 11B, 11C Heat storage material introduction hole, 12A, 12B, 12C Heat medium inlet hole, 13A, 13B, 13C Heat medium outlet hole, 14B, 14C, 15B, 15C Packing.

Claims (5)

It is a heat storage device in which a plurality of plates are laminated, and a latent heat storage material filling space and a heat medium passage space are alternately installed,
Comprising a porous metal provided in a filling space of the latent heat storage material,
The latent heat storage material is filled in the pores of the porous metal.   The heat storage device according to claim 1, wherein the thickness of the layer of the latent heat storage material filling space is set to a value larger than the thickness of the layer of the flow path space of the heat medium. The latent heat storage material filling space includes a plurality of stacked spaces, and includes a manifold space that communicates all of the latent heat storage material filling spaces,
The heat storage device according to claim 1, wherein the manifold space has a buffer space that is not filled with the latent heat storage material.   The heat storage device according to any one of claims 1 to 3, wherein the porous metal is made of foam metal, metal wool, sintered metal, or metal honeycomb.   The heat storage device according to any one of claims 1 to 3, wherein the porous metal is composed of laminated metal meshes.

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